Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
  • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/16—Layered products comprising a layer of synthetic resin specially treated, e.g. irradiated
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
  • B32B27/20—Layered products comprising a layer of synthetic resin characterised by the use of special additives using fillers, pigments, thixotroping agents
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2250/00—Layers arrangement
  • B32B2250/24—All layers being polymeric
  • B32B2250/242—All polymers belonging to those covered by group B32B27/32
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/30—Properties of the layers or laminate having particular thermal properties
  • B32B2307/31—Heat sealable
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/40—Properties of the layers or laminate having particular optical properties
  • B32B2307/406—Bright, glossy, shiny surface
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/40—Properties of the layers or laminate having particular optical properties
  • B32B2307/412—Transparent
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
  • B32B2307/514—Oriented
  • B32B2307/518—Oriented bi-axially
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
  • B32B2307/536—Hardness
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
  • B32B2307/54—Yield strength; Tensile strength
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/70—Other properties
  • B32B2307/724—Permeability to gases, adsorption
  • B32B2307/7242—Non-permeable
  • B32B2307/7246—Water vapor barrier
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/70—Other properties
  • B32B2307/75—Printability
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2439/00—Containers; Receptacles
  • B32B2439/40—Closed containers
  • B32B2439/46—Bags
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2439/00—Containers; Receptacles
  • B32B2439/40—Closed containers
  • B32B2439/62—Boxes, cartons, cases
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2439/00—Containers; Receptacles
  • B32B2439/70—Food packaging
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/249921—Web or sheet containing structurally defined element or component
  • Y10T428/249953—Composite having voids in a component [e.g., porous, cellular, etc.]

Definitions

• the present invention relates to the use of an opaque polypropylene film in a VFFS process.
• Biaxially oriented polypropylene films are today used as packaging films in a wide variety of applications.
• Polypropylene films are characterized by many advantageous performance properties such as high transparency, gloss, barrier to water vapor, good printability, rigidity, puncture resistance, etc.
• opaque polypropylene films have developed very successfully in recent years. On the one hand, the special appearance (opacity and whiteness) of these films is particularly desirable for some applications. On the other hand, opaque films offer the user a higher yield due to the reduced density of these films.
• the polypropylene film must often be combined with other materials to compensate for certain deficiencies.
• different properties are required that can not all be realized on a single film. For this reason, you often add different types of film to a so-called laminate together.
• the lamination requires adhesives or adhesion promoters which cause the laminated films to adhere sufficiently tightly together.
• a coating or painting of the base film to ensure the desired performance characteristics.
• coatings improve the scratch resistance, gloss, or barrier properties of the films, or impart better or different sealing properties, for example, with cold seal adhesive.
• Base film and processing methods must be coordinated so that at the end of the finishing chain results in a packaging that meets the high visual and technical requirements.
• UV curing is a photochemical process in which photoinitiators under the influence of UV light inks and binders form within a few seconds a dry solid ink film. Unlike conventional systems, there are no evaporations of solvents or diluents. All components are involved in the reaction. This makes UV curing a very clean technology.
• EHS electron beam hardening
• the energy of the electrons in electron beam curing can vary and determines the depth of penetration into the material and thus the thickness of the coating, which can be cured or dried.
• the problem with these ESH methods are undesirable interactions with the carrier material.
• the penetration depth of the electrons can not be controlled so precisely during the irradiation that penetration of the electrons into the support material can be completely prevented. This can lead to crosslinking reactions in the support material, sometimes resulting in yellowing, embrittlement or loss of strength.
• the coated or printed and dried by electron beam or cured film product should be used for sealing and hot tack applications.
• the object underlying the invention is achieved by the use of a co-extruded, multi-layer, biaxially oriented polypropylene multilayer film in electron beam curing, which has at least one first sealable cover layer and a vacuole-containing layer with a thickness of at least 5 ⁇ m.
• the vakuolen inconvenience layer of the film is generally the base layer or an intermediate layer of the film.
• vakuolen inconvenience intermediate layers may be present on both sides, which can be combined as an additional option with a vacuole-containing base layer.
• the opaque vacuole-containing layer prevents damage to the sealant layer upon electron beam curing, so that sealant properties, and in particular the hottack of the film, are very good.
• high irradiation intensities or energies can be selected without the hot tack of the film being impaired.
• the base layer is that layer of the film which makes up at least 40%, preferably more than 50% of the total thickness of the film.
• the first cover layer may be applied directly to the base layer.
• additional layers may additionally be provided between this first sealable cover layer and the base layer, which then form one or more first intermediate layer (s).
• cover layers are the outer layers of the coextruded film.
• a second optional cover layer on the opposite side of the base layer may be applied directly to the base layer.
• both cover layers are applied to intermediate layers of the film. Foils in the sense of the present invention can therefore basically comprise 2 to 7-layered embodiments. It is essential that the film structure comprises at least one vacuole-containing layer and at least one sealable cover layer.
• the opaque film according to the invention is distinguished by excellent hot tack values after electron irradiation, which can not be achieved on transparent or white films of comparable construction.
• the first, sealable, coextruded cover layer of the opaque film is generally composed of customary sealable olefinic polymers, for example of ethylene or propylene polymers.
• the sealable, first outer layer contains at least 80% by weight, preferably from 85 to ⁇ 100% by weight, in particular from 95 to 99% by weight, of the stated polymers or mixtures thereof, and optionally conventional additives in respective effective amounts.
• Propylene polymers are copolymers which predominantly contain propylene units.
• Propylene copolymers or terpolymers are generally composed of at least 50% by weight of propylene and ethylene and / or butylene units as comonomer.
• Preferred copolymers for the sealable top layer are ethylene-propylene random copolymers having an ethylene content of from 2 to 10% by weight, preferably from 5 to 8% by weight, or propylene-butylene-1 random copolymers having a butylene content of from 4 to 25 % By weight, preferably 10 to 20% by weight, each based on the total weight of the copolymer, or ethylene-propylene-butylene-1 random terpolymers having an ethylene content of 1 to 10% by weight, preferably 2 to 6 wt .-%, and a butylene-1 content of 3 to 20 wt .-%, before ⁇ zugt 8 to 10 wt .-%, each based on the total weight of
• copolymers and terpolymers generally have a melt flow index of 3 to 15 g / 10 min, preferably 3 to 9 g / 10 min (230 ° C, 21.6N DIN 53735) and a melting point of 70 to 145 ° C, preferably 90 to 140 ° C (DSC).
• Suitable polyethylenes are, for example, HDPE, MDPE, LDPE, LLDPE, VLDPE, of which HDPE and MDPE types are particularly preferred.
• the HDPE generally has an MFI (50 N / 190 C) of greater than 0.1 to 50 g / 10 min, preferably 0.6 to 20 g / 10 min, measured according to DIN 53 735 and a viscosity number, measured according to DIN 53728, Part 4, or ISO 1191, in the range of 100 to 450 cm 3 / g, preferably 120 to 280 cm 3 / g.
• the crystallinity is 35 to 80%, preferably 50 to 80%.
• the density, measured at 23 C according to DIN 53479, method A, or ISO 1183, is in the range of> 0.94 to 0.96 g / cm 3 .
• the melting point, measured with DSC (maximum of the melting curve, heating rate 20 C / min), is between 120 and 140 C.
• Suitable MDPE generally has an MFI (50 N / 190 C) of greater than 0.1 to 50 g / 10 min , preferably 0.6 to 20 g / 10min, measured according to DIN 53735.
• the density, measured at 23 C according to DIN 53479, method A, or ISO 1183, is in the range of> 0.925 to 0.94 g / cm 3 .
• the melting point, measured by DSC (maximum of the melting curve, heating rate 20 C / min), is between 115 and 130 ° C.
• the first sealable topcoat may contain conventional additives such as lubricants, antistatics, antiblocking agents, stabilizers and / or neutralizing agents in respective effective amounts.
• the surface of the first cover layer can be subjected to a method for increasing the surface tension in a manner known per se by means of corona, flame or plasma. Typically, then the surface tension of the thus treated cover layer is in a range of 35 to 45 mN / m. Pre-treatment and additivation must be coordinated so that the sealing and hot-tack properties are not negatively affected.
• the film contains at least one layer, optionally several layers with vacuoles. These vacuoles give the film an opaque appearance and reduce the density of the film relative to the density of the starting materials.
• opaque film means a vacuolate-containing film whose light transmittance (ASTM-D 1003-77) is at most 70%, preferably at most 50%.
• the vacuole-containing layer contains polyolefin, preferably a propylene polymer and vacuole-initiating fillers, and optionally further conventional additives in respective effective amounts.
• the vacuole-containing layer contains at least 70% by weight, preferably 75 to 98% by weight, in particular 85 to 95% Wt .-%, of the polyolefin, each based on the weight of the layer.
• the vacuole-containing layer may contain pigments, in particular TiO 2 , in addition to the vacuole-initiating fillers.
• propylene polymers are preferred. These propylene polymers contain 90 to 100 wt .-%, preferably 95 to 100 wt .-%, in particular 98 to 100 wt .-%, of propylene units and have a melting point of 120 ° C or higher, preferably 150 to 170 ° C, and im in general a melt flow index of 1 to 10 g / 10 min, preferably 2 to 8 g / 10 min, at 230 ° C and a force of 21.6 N (DIN 53735).
• the stated weight percentages refer to the respective polymer.
• Suitable other polyolefins in the polymer mixture are polyethylenes, in particular HDPE, MDPE, LDPE, VLDPE and LLDPE, the proportion of these polyolefins in each case not exceeding 15% by weight, based on the polymer mixture.
• the opaque vacuolate-containing layer of the film generally contains vacuole-initiating fillers in an amount of at most 30% by weight, preferably from 2 to 25% by weight, in particular from 2 to 15% by weight, based on the weight of the vacuolate-containing layer.
• vacuole-initiating fillers are solid particles that are incompatible with the polymer matrix and result in the formation of vacuole-like voids upon stretching of the film, the size, nature, and number of vacuoles being dependent upon the amount and size of the solid particles and stretching conditions such as Stretch ratio and stretching temperature are dependent.
• the vacuoles reduce the density and give the films a characteristic pearlescent, opaque appearance, which results from light scattering at the "vacuole / polymer matrix" interfaces. The light scattering on the solid particles themselves contributes to the opacity of the film in general comparatively little.
• the vacuole-initiating fillers have a minimum size of 1 ⁇ m in order to produce an effective, ie to make an opacifying amount of vacuoles.
• the average particle diameter of the particles is 1 to 6 ⁇ m, preferably 1 to 4 ⁇ m.
• the chemical character of the particles plays a minor role.
• Typical vacuole-initiating fillers are inorganic and / or organic, polypropylene incompatible materials such as alumina, aluminum sulfate, barium sulfate, calcium carbonate, magnesium carbonate, silicates such as aluminum silicate (kaolin clay) and magnesium silicate (talc) and silica, among which calcium carbonate and silica are preferably used.
• Suitable organic fillers are the polymers customarily used which are incompatible with the polymer of the base layer, in particular copolymers of cyclic olefins (COC) as in EP-A-0623 463 described polyesters, polystyrenes, polyamides, halogenated organic polymers, with polyesters such as polybutylene terephthalates and cycloolefin copolymers are preferred.
• COC cyclic olefins
• Incompatible materials or incompatible polymers in the sense of the present invention means that the material or the polymer is present in the film as a separate particle or as a separate phase.
• the vacuole-containing layer may additionally contain pigments, for example in an amount of 0.5 to 10 wt .-%, preferably 1 to 8 wt .-%, in particular 1 to 5 wt .-%.
• the data relate to the weight of the vacuole-containing layer.
• pigments are incompatible particles which essentially do not lead to the formation of vacuoles during stretching of the film.
• the coloring effect of the pigments is caused by the particles themselves.
• the term “pigments” is generally bound to an average particle diameter in the range of 0.01 to a maximum of 1 micron and includes both so-called “white pigments", which color the films white, as well as “colored pigments", which the film a colorful or black Give color.
• the average particle diameter of the pigments is in the range from 0.01 to 1 ⁇ m, preferably 0.01 to 0.7 ⁇ m, in particular 0.01 to 0.4 ⁇ m.
• Typical pigments are materials such as alumina, aluminum sulfate, barium sulfate, calcium carbonate, magnesium carbonate, silicates such as aluminum silicate (kaolin clay) and magnesium silicate (talc), silica and titania, among which white pigments such as calcium carbonate, silica, titania and barium sulfate are preferably used.
• silicates such as aluminum silicate (kaolin clay) and magnesium silicate (talc)
• silica and titania among which white pigments such as calcium carbonate, silica, titania and barium sulfate are preferably used.
• Titanium dioxide is particularly preferred.
• modifications and coatings of TiO 2 are known per se in the art.
• the density of the film is substantially determined by the density of the vacuolated layer.
• the density of the vacuole-containing layer is generally determined by the Vacuoles may be reduced unless larger amounts of TiO 2 compensate for the density reducing effect of the vacuoles.
• the density of the opaque vacuolate-containing layer is in the range of 0.45-0.85 g / cm 3 .
• the density of the film may vary within a wide range for the various embodiments, and is generally in the range of 0.5 to 0.95 g / cm 3 , preferably 0.6 to 0.9 g / cm 3 .
• the density is generally increased by the addition of TiO 2 , but at the same time lowered by the vacuole-initiating fillers in the vacuole-containing layer.
• the density of the opaque vacuolate-containing layer is preferably in a range of 0.45 to 0.75 g / cm 3 , whereas for the white-opaque vacuolated layer containing TiO 2 the range is 0.6 to 0.9 g / cm 3 is preferred
• the above-described vacuole-containing layer is the base layer of the film and then has a thickness of at least 10 to 80 ⁇ m, preferably 10 to 60 ⁇ m.
• the vacuolate-containing layer may also be an intermediate layer, or the film may have one or two vacuole-containing intermediate layers in addition to the vacuole-containing base layer.
• the vacuolate-containing layer is generally at least 5 ⁇ m, preferably 7 to 15 ⁇ m thick.
• the total thickness of the film is generally in a range of 20 to 100 .mu.m, preferably 25 to 60 .mu.m, in particular 30 to 50 .mu.m.
• the film still comprises an additional layer or layers which is / are not vacuolated.
• This additional layer or layers is, for example, a second cover layer and / or one or two additional intermediate layers.
• the additional vacuole-free layer may also be the base layer of the film. Structure and composition of the additional layer or layer depends on the desired functionality, which is to be introduced into the film.
• the thickness of the additional layer as the second cover layer is generally 0.5-3 ⁇ m, and additional non-vacuole-containing intermediate layer generally has a thickness in the range of 1 to 8 ⁇ m.
• the additional non-vacuole-containing layer (s) generally contain at least 80% by weight, preferably 90 to ⁇ 100% by weight, of olefinic polymers or mixtures thereof.
• Suitable polyolefins are, for example, polyethylenes, propylene copolymers and / or propylene terpolymers, as well as the propylene homopolymers already described in connection with the vacuole-containing layer, as well as optionally additionally customary additives.
• Suitable propylene copolymers or terpolymers are generally composed of at least 50% by weight of propylene and ethylene and / or butylene units as comonomer.
• Preferred copolymers are ethylene-propylene random copolymers having an ethylene content of from 2 to 10% by weight, preferably from 5 to 8% by weight, or random propylene-butylene-1 copolymers having a butylene content of from 4 to 25% by weight.
• copolymers and terpolymers generally have a melt flow index of 3 to 15 g / 10min, preferably 3 to 9 g / 10min (230 ° C, 21.6N DIN 53735) and a melting point of 70 to 145 ° C, preferably 90 to 140 ° C (DSC).
• Suitable polyethylenes are, for example, HDPE, MDPE, LDPE, LLDPE, VLDPE, of which HDPE and MDPE types are particularly preferred.
• the HDPE generally has an MFI (50 N / 190 C) of greater than 0.1 to 50 g / 10 min, preferably 0.6 to 20 g / 10 min, measured according to DIN 53 735 and a viscosity number, measured according to DIN 53728, Part 4, or ISO 1191, in the range of 100 to 450cm 3 / g, preferably 120 to 280cm 3 / g.
• the crystallinity is 35 to 80%, preferably 50 to 80%.
• the density, measured at 23 C according to DIN 53479, method A, or ISO 1183, is in the range of> 0.94 to 0.96 g / cm 3 .
• the melting point, measured with DSC (maximum of the melting curve, heating rate 20 C / min), is between 120 and 140 C.
• Suitable MDPE generally has an MFI (50 N / 190 C) of greater than 0.1 to 50 g / 10 min , preferably 0.6 to 20 g / 10 min, measured according to DIN 53 735.
• the density, measured at 23 C according to DIN 53479, method A, or ISO 1183, is in the range of> 0.925 to 0.94 g / cm 3.
• the melting point, measured by DSC (maximum of the melting curve, heating rate 20 C / min) is between 115 and 130 ° C.
• the additional non-vacuole-containing layers may be added to the pigments described above for the base layer, in particular TiO 2 in an amount of from 2 to 12% by weight, preferably from 3 to 8% by weight. -% based on the weight of the layer.
• all layers of the film preferably contain neutralizing agents and stabilizers in respective effective amounts, as well as optionally additionally conventional additives such as lubricants, antistatic agents or antiblocking agents.
• the usual stabilizing compounds for ethylene, propylene and other olefin polymers can be used. Their additional amount is between 0.05 and 2 wt .-%. Particularly suitable are phenolic stabilizers, alkali metal / alkaline earth metal stearates and / or alkali metal / alkaline earth metal carbonates. Phenolic stabilizers are used in an amount of 0.1 to 0.6 wt .-%, in particular 0.15 to 0.3 wt .-%, and with a molecular weight of more than 500 g / mol preferred.
• Pentaerythrityl tetrakis-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate or 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxy ⁇ benzyl) benzene are particularly advantageous.
• Neutralizing agents are preferably calcium stearate and / or calcium carbonate and / or synthetic dihydrotalcite (SHYT) having an average particle size of at most 0.7 ⁇ m, an absolute particle size of less than 10 ⁇ m and a specific surface area of at least 40 m 2 / g. In general, neutralizing agents are used in an amount of 50 to 1000 ppm based on the layer.
• SHYT synthetic dihydrotalcite
• Suitable antiblocking agents are inorganic additives such as silica, calcium carbonate, magnesium catamaran, aluminum silicate, calcium phosphate and the like and / or incompatible polymers such as polymethyl methacrylate (PMMA) polyamides, polyesters, polycarbonates and the like, preferably polymethylmethacrylate (PMMA), silica and calcium carbonate.
• PMMA polymethyl methacrylate
• the effective amount of antiblocking agent is in the range of 0.1 to 2 wt .-%, preferably 0.1 to 0.5 wt .-%, based on the respective cover layer.
• the average particle size is between 1 and 6 microns, in particular 2 and 5 microns, wherein particles having a spherical shape, as in EP-A-0 236 945 and the DE-A-38 01 535 described, are particularly suitable.
• the above-described film according to the invention is subjected to a suitable processing method in which electron beam curing is used.
• the film can for example be printed, laminated, laminated, painted, coated or provided with a cold seal adhesive.
• these processing steps can also be combined with each other, for example, first a print with subsequent overpainting.
• the additional layers or films are applied to the first sealable cover layer opposite side. The drying or curing of the adhesives, paints or coatings takes place by means of an electron beam hardening method.
• the processed film can be used as a sealable film for the production of packaging. Despite the drying or hardening by means of electron beams, the film shows excellent sealing and excellent hot tack values, which are essential when filling a sealed edge bag.
• the invention further relates to a process for producing the multilayer film according to the invention by the known coextrusion process, wherein in particular the stenting process is preferred.
• melts corresponding to the individual layers of the film are coextruded through a flat die, the resulting film removed for solidification on one or more rolls, the film subsequently stretched, the heat-set stretched film and optionally cured the surface layer intended for the treatment is plasma corona or flame treated.
• the polymer or the polymer mixture of the individual layers is compressed and liquefied in an extruder, wherein the Vakuoleninit Schlour fillers and other given ⁇ if added additives may already be contained in the polymer or in the polymer mixture. Alternatively, these additives can also be incorporated via a masterbatch.
• melts are then pressed together and simultaneously through a flat die (slot die), and the ⁇ pressed multilayer film is drawn on one or more peel-off rolls at a temperature of 5 to 100 ° C, preferably 10 to 50 ° C cools and solidifies.
• the resulting film is then stretched longitudinally and transversely to the extrusion direction, resulting in orientation of the molecular chains.
• the longitudinal stretching is preferably carried out at a temperature of 80 to 150 ° C advantageously with the help of two corresponding to the desired stretch ratio different speed rolling rolls and the transverse stretching preferably at a temperature of 120 to 170 ° C by means of a corresponding clip frame.
• the longitudinal stretch ratios are in the range of 4 to 8, preferably 4.5 to 6.
• the transverse stretch ratios are in the range of 5 to 10, preferably 7 to 9.
• the stretching of the film is followed by its heat setting (heat treatment), the film being kept at a temperature of 100 to 160 ° C. for about 0.1 to 10 seconds. Subsequently, the film is wound in the usual manner with a winding device.
• one or both surfaces of the film are / are plasma, corona or flame treated by one of the known methods.
• the treatment intensity is generally in the range of 35 to 50 mN / m, preferably 37 to 45 mN / m, in particular 39 to 40mN / m.
• the melt flow index was measured according to DIN 53 735 at 21.6 N load and 230 ° C.
• the density is determined according to DIN 53 479, method A.
• the surface tension was determined by ink method according to DIN 53 364.
• Hot-Tack refers to the strength of a still hot sealed seam immediately after opening the sealing tools.
• two foil blanks of 530 mm are superimposed and fixed at the ends with a staple weight G of 100 g.
• a flat spatula is inserted between the foil layers, and the measuring strip is guided between the sealing jaws via two deflection rollers. Subsequently, the seal is released, the spatula is pulled between the layers as soon as the sealing jaws are closed.
• the sealing conditions are 150 ° C for the sealing temperature, 0.5 s for the sealing time and 30 N / cm2 for the contact pressure.
• the sealing jaws (area: 20 cm 2) open automatically, and the sealed measuring strip is pulled forward jerkily up to the deflection roller by the load weight and split at a separation angle of 180 °.
• the hot-tack is the depth of the delamination of the sealed seam in mm, which it experiences at the given force.
• a five-layer prefilm was extruded from a slot die at an extrusion temperature of 240 to 270 ° C. This prefilm was first stripped off on a chill roll and cooled. Subsequently, the prefilm was oriented in the longitudinal and transverse directions and finally fixed. The surface of the second cover layer was pretreated by corona to increase the surface tension.
• the five-layered film had a layer structure first cover layer / first intermediate layer / base layer / second intermediate layer / second cover layer.
• the individual layers of the film had the following composition:
• Second cover layer (1.0 ⁇ m):
• All layers of the film additionally contained stabilizer and neutralizing agent in conventional amounts.
• Extrusion temperature about 250-270 ° C
• Cooling roller temperature 30 ° C
• the film was surface treated on the surface of the second cover layer by corona and had a surface tension of 38mN / m.
• the film had a thickness of 40 microns and an opaque appearance.
• Example 1 An opaque film according to Example 1 was produced. In contrast to Example 1, no CaCo3 was added to the base layer, the proportion of propylene homopolymer correspondingly increased.
• the film had a density of 0.96 cm 3 ; a thickness of 30.. ⁇ m and a white appearance.
• Example 2 A film was produced as described in Example 1. In contrast to Example 1, no layer of TiO 2 or CaCO 3 was added. In this way, a transparent film having a density of 0.9 g / cm 3 was obtained
• the hot-tack values remain almost constant only in the case of the opaque films of the invention which are opaque. There is only a marginal impairment of the hot tack as the dosage increases.
• the white or transparent films according to VB2 and VB3 show an increasing deterioration of the hot tack with increasing load on the film at higher sealing temperatures.
• the opaque film according to the invention can thus be used very variably in the ESH process without adversely affecting the hot tack.
• the film can still be sealed in a very wide temperature range after electron beam treatment and shows stable and good hot tack values of 90-140 ° C. In the transparent and white films, the sealing layer is damaged by the irradiation.
• This damage increases with increasing intensity of the electron beams, so that this film can either be irradiated only with low-energy electrons or a very narrow processing window must be taken into account.
• the film shows only at sealing temperatures of about 120 ° C an acceptable hot-tack, which is only slightly worse compared to the untreated film.

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• 2006
  • 2006-05-17 WO PCT/EP2006/062395 patent/WO2006122958A1/de not_active Application Discontinuation
  • 2006-05-17 EP EP20060763176 patent/EP1885559B1/de not_active Not-in-force
  • 2006-05-17 US US11/914,573 patent/US8641854B2/en not_active Expired - Fee Related
  • 2006-05-17 PL PL06763176T patent/PL1885559T3/pl unknown
  • 2006-05-17 ES ES06763176T patent/ES2397871T3/es active Active
  • 2006-05-17 PT PT06763176T patent/PT1885559E/pt unknown

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